1. Field of the Invention
The present invention relates generally to medical methods, devices, and systems. In particular, the present invention relates to methods, devices, and systems for the endovascular, percutaneous or minimally invasive surgical treatment of bodily tissues, such as tissue approximation or valve repair. More particularly, the present invention relates to repair of valves of the heart and venous valves.
Mitral valve regurgitation is characterized by retrograde flow from the left ventricle of a heart through an incompetent mitral valve into the left atrium. During a normal cycle of heart contraction (systole), the mitral valve acts as a check valve to prevent flow of oxygenated blood back into the left atrium. In this way, the oxygenated blood is pumped into the aorta through the aortic valve. Regurgitation of the valve can significantly decrease the pumping efficiency of the heart, placing the patient at risk of severe, progressive heart failure.
Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve or the left ventricular wall. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, the papillary muscles or the left ventricular wall may be damaged or otherwise dysfunctional. Commonly, the valve annulus may be damaged, dilated, or weakened limiting the ability of the mitral valve to close adequately against the high pressures of the left ventricle.
The most common treatments for mitral valve regurgitation rely on valve replacement or repair including leaflet and annulus remodeling, the latter generally referred to as valve annuloplasty. A recent technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the “bow-tie” or “edge-to-edge” technique. While all these techniques can be very effective, they usually rely on open heart surgery where the patient's chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated high mortality and morbidity. More recently, minimially invasive catheter based procedures have been developed to deliver implantable clips to the incompetent valve. These clips are used to fasten a portion of the valve leaflets together, thereby reducing the regurgitation. While the clips appear to be promising, delivery and deployment of the clip can be challenging. In some situations, it may be challenging to visualize the clip and valve leaflets using techniques such as fluoroscopy and echocardiography. Therefore, improved attachment mechanisms and attachment evaluation methods would be desirable.
For these reasons, it would be desirable to provide improved methods, devices, and systems for performing the repair of mitral and other cardiac valves. Such methods, devices, and systems should preferably not require open chest access and be capable of being performed either endovascularly, i.e., using devices which are advanced to the heart from a point in the patient's vasculature remote from the heart or by a minimally invasive approach. Further, such devices and systems should provide features which allow easier delivery of fixation devices, as well as repositioning and optional removal of the fixation device prior to fixation to ensure optimal placement. Still more preferably, the methods, devices, and systems would be useful for repair of tissues in the body other than heart valves. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Related Art
Minimally invasive and percutaneous techniques for coapting and modifying mitral valve leaflets to treat mitral valve regurgitation are described in PCT Publication Nos. WO 98/35638; WO 99/00059; WO 99/01377; and WO 00/03759.
Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci et al. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al. (1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgical procedures for performing “edge-to-edge” or “bow-tie” mitral valve repair where edges of the opposed valve leaflets are sutured together to lessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med. 331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg. 112:238-247 are review articles discussing the nature of and treatments for dilated cardiomyopathy.
Mitral valve annuloplasty is described in the following publications. Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996) Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J. 129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmental annuloplasty for mitral valve repair is described in Ricchi et al. (1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty is described in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268; Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989) Ann. Thorac. Surg. 48:670-676.
Percutaneous transluminal cardiac repair procedures are described in Park et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am. Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc. Diagn. 23:257-262.
Endovascular cardiac valve replacement is described in U.S. Pat. Nos. 5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854. See also U.S. Pat. No. 3,671,979 which describes a catheter for temporary placement of an artificial heart valve.
Other percutaneous and endovascular cardiac repair procedures are described in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and PCT Publication No. WO 91/01689.
Thoracoscopic and other minimally invasive heart valve repair and replacement procedures are described in U.S. Pat. Nos. 5,855,614; 5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.